The present invention generally relates to optical interconnects and systems including optical interconnects. More particularly, the invention relates to optical interconnects and systems suitable for providing a transmission path between optoelectronic devices and/or between an optoelectronic device and a waveguide such as a fiber ribbon and to methods of forming the interconnects and systems.
Systems including optical interconnect devices are often used to transmit information at high data rates. For example, such systems are used for board-to-board, backplane, local area network (LAN), wide area network (WAN) and similar applications. Optical systems are advantageous compared to electrical interconnect systems because optical systems are generally less susceptible to electromagnetic interference, which often results in cross-talk within the system and external noise emission from the system, particularly as the rate of information transfer increases. However, optical interconnect systems are typically relatively expensive compared to electrical interconnect systems, and thus factors such as distance the transmitted signal must travel, bandwidth required by the system, cost, power consumption, signal integrity requirements, and the like are often considered before selecting a type of system.
Typical optical interconnect systems generally include an optoelectronic device such as a light emitting (e.g., laser) and/or a light detecting (e.g., a photodiode) device, an electronic device (e.g., an amplifier and/or a driver) coupled to the optoelectronic device, and waveguide material such as a fiber ribbon cable. The optoelectronic devices are often fabricated such that the active region. i.e., the area that emits or receives photos from the waveguide, is on the same surface as electrical connections for coupling the optoelectronic device to the corresponding electrical device. In this case, either the electrical connections or the optical connections must typically undergo an effective ninety degree bend to allow electrical coupling between the optoelectronic device and electronic device and optical coupling between the optoelectronic device and the waveguide. Prior-art methods and apparatus for coupling light between an optoelectronic device and a waveguide are generally relatively expensive to manufacture and/or are relatively inefficient at transferring light between the optoelectronic device and the waveguide. Accordingly, improved methods and apparatus for coupling an optoelectronic device to a waveguide and methods of forming the apparatus are desired.
The present invention provides an apparatus for coupling an optoelectronic device to a optical transmission medium or waveguide such as an optical fiber and a method of forming the apparatus. More particularly, the invention provides an optical interconnect device including reflective and focusing surfaces, systems including the device, and methods of forming the device and system.
The way in which the present invention addresses various drawbacks of the now-known optical interconnect devices and systems is discussed in greater detail below. However, in general, the improved optical interconnect device and system in accordance with the present invention are relatively inexpensive and easy to manufacture.
In accordance with one embodiment of the present invention, a waveguide and a reflective surface are formed on a surface of a substrate. In accordance with one aspect of this embodiment, the waveguide is formed by depositing waveguide material such as SiN, SiOx, polymer material, or the like, patterning the material, and etching the material to form a desired pattern. In accordance with a further aspect of this embodiment, the waveguide material is patterned and etched to form a curved portion, suitable for focusing light, on one end of the waveguide. In accordance with one particular aspect of this embodiment, the waveguide material includes silicon oxide and is deposited using flame hydrolysis deposition. Cladding layers for the waveguide may be formed by depositing material about the waveguide and/or by implanting material into the waveguide to change the index of refraction of a portion of the waveguide material. Gratings on the waveguide material may be formed by one of several approaches. For example, gratings can be formed on waveguides using a mask and ultraviolet light exposure or by patterning photoresist material, exposing the patterned photoresist to ultraviolet radiation, and etching the unexposed waveguide material. In accordance with yet another aspect of this embodiment, the reflective surface is formed by etching a portion of a substrate material to form a reflective structure, and if desired, coating at least a portion of the reflective structure with a reflective material to increase the reflectivity of the surface.
In accordance with another embodiment of the invention, a reflective surface, which both reflects light to a desired direction and focuses the light to a desired location, is formed on a surface on a substrate. In accordance with one aspect of this embodiment, the reflective surface is formed by depositing a material such as silicon oxide patterning the silicon oxide material, and etching the material to form, e.g., a parabolic or ellipsoid surface, which if desired, may be coated with a reflective substance.
In accordance with a further embodiment of the invention, the reflective surface may be formed within a substrate by etching the substrate to formed the reflective surface, which, if desired, may be coated with a reflective material.